The present invention relates to flexible containers to be filled with bulk material, and specifically to such containers having integral lifting loops and which may be manufactured from flat-woven or round-woven base material joined together for forming the lifting loops.
Containers of the above mentioned type have been used for some time and been found to be suitable for several purposes. Usually they have an inner bag or liner of impervious material. The container is usually first blown up by air before it is filled with free-flowing bulk material. Such a container is described in U.S. Pat. No. 4,136,723. This container has a double bottom and is preferably equipped with two integrated lifting loops having a total width substantially equal to half of the container circumference such that the lifting loops are formed of all of the longitudinal fibers of the container. The container can be filled by using an apparatus described in G.B. Pat. No. 1.505.583, and it will then stand on a floor or the like without any extra support. The lifting loops can be placed on a hook or the like before the container is blown up and filled with bulk material. The container can then be made ready for further transport, and this process might comprise closing the inner bag and joining the lifting loops by pressing them together and securing them in this position to obtain a suitable loop or handle which easily can be placed on a hook or some other lifting means. If a broad hook is employed to hang the lifting loops during the filling operation, the wide loops may be pressed together to a few cm and can be kept in this position by means of a tape. One will then obtain a well-defined loop which makes the container well suited for further transport, and this is described in EP-application No. 81108748,5 (publication No. 54145).
However, it has been found that the above mentioned process for making the container ready beforehand also has certain disadvantages. Also, when the container lifting loops are made ready after filling, there occur certain drawbacks. Thus the capacity of the filling apparatus will be reduced because of the time it takes for the operator to place the lifting loops onto a hook which will press them together. If this operation is carried out after the container is filled in order to improve the capacity of the apparatus, then the total filling operation will be more labour-consuming because an extra operator is needed for making the container loops ready. Further, the container's form itself implies that it is necessary to use filling apparatuses of a special type in order to obtain efficient filling and an effective process for making such containers ready. The fact that such special filling apparatuses are not available at all locations where filling of such containers might take place has accordingly hindered widespread use of the container.
The lifting loops may have a total width corresponding to half the container circumference, the result of which is that the process of joining together the loops to form one lifting loop or handle becomes somewhat labour-consuming. The wide loops also result in certain disadvantages when the container is placed on the filling apparatus or connected to it. Accordingly, there has been a need for making these operations easier and less labour-consuming.
One would like to continue having some form of lifting loops because of the good experience with integral lifting loops which, after filling of bulk material into the container, may be joined together by tape to form a transport lifting loop. During further transport of the container such lifting loops have been found to be suitable for receiving lifting hooks, forks and other means used for lifting and transporting the container.
When fork trucks are used, a special lifting device, on which the lifting loop is placed, is connected to the forks. It has further been found that the tape applied in certain cases can be damaged during the further lifting and transport of the container, especially if there are applied lifting forks having sharp edges, the load-carrying fibers of the material of the lifting loop can also be damaged.
In such cases there is therefore a need for a better protection of the fibers of the material of the lifting loop and a way of joining which can endure the strain when lifting forks are applied.